+Cc: Hans. On Wed, 2017-06-21 at 16:40 +0200, Ulf Hansson wrote: > On 20 June 2017 at 18:08, Andy Shevchenko > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > On Tue, 2017-06-20 at 15:07 +0200, Ulf Hansson wrote: > > > On 16 June 2017 at 15:49, Ulf Hansson <ulf.hansson@xxxxxxxxxx> > > > wrote: > > > > Jarkko, Andy, > > > > > > > > I just wanted to mention that I haven't forgot about this, I am > > > > doing > > > > the final changes for the ACPI PM domain at this very moment, > > > > however > > > > I need a couple of more days more before I can post something. > > > > > > I have gone through the series briefly. > > My concern is a quite nasty bug we have workaround for in > > acpi_lpss.c, > > i.e. auto power gating of DesignWare DMA on Intel Braswell > > (CherryTrail) > > platforms when it's enumerated via ACPI. > > First, as long as there is no driver calling the new API > acpi_dev_disable_direct_comlete(), the ACPI PM domain should behave > exactly the same as before these changes. > > However, regarding your concern, can you please be a bit more precise > on how you deal with the problems. I would appreciate if you could > give me real pointers to the code for the workaround, the above is too > hand wavy for me to understand. In acpi_lpss.c there are big comments about this issue. Hans, Cc'ed, is working on that in relation to PWM power problems. > > So where things really starts to change is in the final i2c patch in > the series, which converts the i2c designware platform driver to use > the runtime PM centric approach, and to do that, it calls the > acpi_dev_disable_direct_complete(). Does it mean we will loose a possibility to use DMA for I2C (not much I care about and would be unlikely a user for this, just wondering)? > > > > Below is the sequence to test if it works and survives removal and > > system sleep (lpss-power.sh is the script which shows a power state > > of > > selected devices along with PMC Atom status registers and runtime > > PM): > > > > 0 lpss-power.sh > > 1 mount -t debugfs none /sys/kernel/debug > > 2 lpss-power.sh > > 3 modprobe i2c-designware-platform > > 4 lpss-power.sh > > 5 modprobe sdhci-acpi > > 6 lpss-power.sh > > 7 lsmod > > 8 modprobe dw-dmac > > 9 lpss-power.sh > > 10 modprobe -r dw-dmac > > 11 lpss-power.sh > > 12 modprobe dw-dmac > > 13 lpss-power.sh > > 14 rtcwake -m mem -s3 > > 15 lpss-power.sh > > 16 modprobe -r dw-dmac > > 17 lpss-power.sh > > 18 modprobe dw-dmac > > 19 lpss-power.sh > > 20 stty -F /dev/ttyS2 921600 > > 21 dmesg > /dev/ttyS2 > > 22 cat /proc/interrupts > > 23 cat < /dev/ttyS1 > > 24 lpss-power.sh > > 25 cat < /dev/ttyS1 & > > 26 lpss-power.sh > > 27 rtcwake -m mem -s3 > > 28 lpss-power.sh > > 29 fg > > 30 lpss-power.sh > > > > Be aware that DMA is not enabled for I2C! > > So if DMA isn't enabled for I2C, what is there to worry about? Since LPSS are all in the same ACPI PM, and I would really carefully change behaviour for any of LPSS component driver without wide testing. -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy
